This invention relates to a process for producing multicolored coverstocks for interior trim parts of vehicles. Specifically this invention relates to a system and process for laminating and embossing two differently colored TPO film sheets to a foam substrate.
Many vehicles such as automobiles have molded parts in their passenger areas which have desirable cosmetic appearances. A common type of cosmetic feature formed on many interior surfaces of automobiles includes an embossed coverstock or skin. Embossed skins may include a raised or recessed grain which resembles an animal hide such as leather. Molded parts with embossed skins may be found on dashboards, doors and other interior portions of an automobile or other vehicle.
In general the embossed skins of many automotive interior parts are formed from a colored thermoplastic laminate which is bonded to a cushioned substrate such as a foam. These skins are generally comprised of a single color. However, for cosmetic purposes, there exists a need for such skins that have two or more adjacent top surfaces which have different colors. Prior art methods for manufacturing such multicolored skins involve the use of specialized molds. Such molds include multiple zones which are separated by partitions positioned at the intended seam between differently colored skin surfaces. Each differently colored skin surface is formed in a different one of the zones of the mold. An example of such a process for producing multicolored surfaces is shown in U.S. Pat. No. 5,262,108 issued Nov. 16, 1993.
Although such methods produce a uniform seam in the location of the partition, the resulting seam includes a visible gap between the differently colored skin surfaces. Such a gap is often cosmetically undesirable for many automobile interior applications. Further the resulting multicolored surface is structurally weaker in the location of the seam between the differently colored skin surfaces than corresponding mono-color skins without such gaps. Consequently, there exists a need for a system and process of producing multicolored skin surfaces which do not include a visible gap between adjacent, differently colored surfaces. There further exists a need for a system and process of producing multicolored skin surfaces which have gapless seams between differently colored surfaces. There further exists a need for a system and process of producing multicolored skin surfaces which have structurally stronger seams joining differently colored surfaces.
It is an object of the exemplary form of the present invention to provide a system and process for forming a thermoplastic coverstock.
It is a further object of the exemplary form of the present invention to provide a system and process for forming a multicolored thermoplastic coverstock.
It is a further object of the exemplary form of the present invention to provide a system and process for forming an embossed multicolored thermoplastic coverstock.
It is a further object of the exemplary form of the present invention to provide a system and process for forming a multicolored thermoplastic coverstock which includes a uniform and cosmetically appealing seam between differently colored adjacent surfaces of the coverstock
It is a further object of the exemplary form of the present invention to provide a system and process for forming a multicolored thermoplastic coverstock which does not include a gap between differently colored adjacent surfaces of the coverstock.
Further objects of the present invention will be made apparent in the following Best Modes for Carrying Out Invention and the appended Claims.
The foregoing objects are accomplished in an exemplary embodiment of the invention by a post embossing and laminating process which is operative to form a multicolored sheet for use as an interior trim coverstock or skin for interior automotive parts. Examples of such interior automotive parts include doors, dashboards, instrument panels, walls, roofs, seating or any other interior part or portion of an automobile or other vehicle which may be covered with a skin. The exemplary process of the present invention is operative to thermally laminate two or more differently colored thermoplastic olefin (TPO) film sheets together. In addition the exemplary embodiment of the present invention is operative to thermally laminate the two or more TPO film sheets to a flexible and soft substrate such as an olefin foam. Further, the exemplary embodiment of the present invention is operative to thermally emboss the two or more TPO sheets with a grain pattern.
The exemplary post embossing and laminating process is operative to form an exemplary multicolored coverstock by passing the two or more TPO sheets and an olefin foam through a series of heated rolls at designated speeds and gaps to achieve the desired product characteristics. In one exemplary embodiment, the process includes providing two or more feed rolls of TPO film sheets, where each sheet has a different cosmetic surface characteristic such as different coloring or other visually distinct quality. The exemplary process further includes providing a substrate sheet such as a foam, fabric or textile backing.
In the exemplary embodiment of the process, the sheets are unwound from the rolls and are directed through an accumulator. The accumulator is operative to compensate for variations in the processing rate of the system by storing and releasing excess unwound film sheets as is needed. In the exemplary process both the sheets and the foam substrate are directed through a plurality of heated rolls. The output of the sheets from the heated rolls is directed through a spreader bar which is reversed to cause the sheets to partially overlap.
In the exemplary embodiment, the partially overlapped sheets are directed through an oven. The oven is operative to raise the temperature of the sheets to a point that is suitable for lamination to the substrate. The output of the overlapped sheets from the oven is directed through an embosser roll system along with the substrate. The embosser roll system is operative to apply sufficient pressure to the overlapped sheets and foam substrate, to laminate or otherwise bond the sheets and the substrate foam together. In addition the embosser roll includes an embossing surface which is operative to impart an embossed grain into the top surface of the overlapped sheets. The resulting embossed coverstock is passed through a series of cooling rolls and is wound on a roll by a winder.